Manufacturers of industrial disposable rigid filter cartridges have for many years essentially standardized filter cartridge diameter and length dimensions and geometries. As a result, the filter cartridges produced by virtually every manufacturer are capable of being employed in another manufacturer's cartridge housing. Nonetheless, there still exists a need for non-standardized filter cartridges to be provided to the industry. For example, the standardized filter cartridge geometry may not be entirely sufficient for use in large filtration installations and/or to filter heavily contaminated fluids. While higher capacity filter cartridge geometries can be envisioned, their commercial acceptance is limited due to the costs associated with the replacement of existing filter cartridge housings designed for use with the conventional standardized filter cartridge geometries.
In now abandoned U.S. application Ser. No. 09/988,222 filed on Nov. 19, 2001, and published under International Publication No. WO03/043714A1 , the entire content of which is expressly incorporated hereinto by reference and will be hereinafter referred to as “the '222 application”, there are disclosed novel length-adjustable filter cartridges having at least one length-adjustable end cap attached to an end of the filter body. The length-adjustable end cap most preferably includes an annular stationary ring member which is attached to one end of the filter body, and a moveable connection member slideably received within the annular stationary ring member so as to be moveable longitudinally relative thereto.
While the end caps and filter cartridges disclosed and claimed in the '222 application are entirely satisfactory, some improvements thereto may still be desired. For example, during the manufacture of the filter cartridges by thermally bonding the end caps to the cylindrical filtration medium, the provision of a separate O-ring seal may be problematic thereby leading to production difficulties. As such, it would be highly desirable if the annular stationary ring member that is thermally bonded to the filter medium could be provided with an annular seal that was formed as a one-piece (unitary) structure therewith. Moreover, it would be desirable if such a seal could be thermally protected during the thermal bonding procedures.
According to the present invention, length-adjustable end caps and filter cartridges including the same are provided. In preferred embodiments, the length-adjustable end caps include a stationary ring member which includes an annular seal, e.g., a lip seal, a spacer coaxially positioned in spaced relationship with the seal, e.g., spaced below the seal, and a connection member in moveable sealing contact with the lip seal and in a sliding fit with the spacer. The connection member includes an outwardly extending flange having an outer region which includes a sealing arrangement. Most preferably, the lip seal is unitary with the stationary ring member and is a segment of a conical surface and thereby has a proximal edge region which is unitarily joined to the ring member and an opposite distal terminal end which projects downwardly and inwardly into the opening defined by the ring member. The stationary ring member preferably includes a connection flange which defines an annular recess concentric with, but spaced from, the unitary lip seal. The spacer may include an annular spacer ring which is received within the recess. During thermal bonding of the connection flange to an end of a generally cylindrical filter medium, the spacer ring and the end of the filter medium will both be thermally melded to respective adjacent portions of the connection flange. As such, the spacer ring will be integrally fused to the ring member.
These and other aspects and advantages will become more apparent after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.